When Scout, Jem, and Dill go to find Atticus and they find out he is in some trouble with a group, who had Atticus covered the whole time?When they...

Mr. Underwood is an ironic man as the story continues. Watch him at the trial. Scout describes his ability to note every detail, which is likely what he was watching the whole time when they were at the jail that night. He was waiting for the right twitch or gesture to show that someone was going to attack Atticus.

Another irony of Mr. Underwood is this ability to print whatever he wants no matter what the people think of his work. As a racist, you'd think he'd print something negative about the trial. He doesn't. Just watch.